Suppose you had a PC/AT (Intel 286) with 1MB of RAM and a tiny
hard drive, and someone handed you an ISA Ethernet card and
told you to "do something useful with it." (Hint: visit
<URL:http://www.crynwr.com/> for Packet Driver information.)

The KA9Q Network Operating System ("KA9Q NOS") is one of the
most flexible MS-DOS applications you could use, offering an
assortment of TCP/IP clients and servers. Since the code is
small, and entirely memory-resident, it can be run off a floppy.
(Some servers, like smtp and pop, really want a hard drive.)
Unfortunately, it calls upon MS-DOS for file I/O...